scholarly journals Photosensitized, energy transfer-mediated organometallic catalysis through electronically excited nickel(II)

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 380-385 ◽  
Author(s):  
Eric R. Welin ◽  
Chip Le ◽  
Daniela M. Arias-Rotondo ◽  
James K. McCusker ◽  
David W. C. MacMillan
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Transition Metal Catalysis ◽  
Organometallic Complexes ◽  
Mechanistic Studies ◽  
Metal Catalysis ◽  
Organometallic Catalysts ◽  
Organometallic Catalysis ◽  
Electronically Excited

Transition metal catalysis has traditionally relied on organometallic complexes that can cycle through a series of ground-state oxidation levels to achieve a series of discrete yet fundamental fragment-coupling steps. The viability of excited-state organometallic catalysis via direct photoexcitation has been demonstrated. Although the utility of triplet sensitization by energy transfer has long been known as a powerful activation mode in organic photochemistry, it is surprising to recognize that photosensitization mechanisms to access excited-state organometallic catalysts have lagged far behind. Here, we demonstrate excited-state organometallic catalysis via such an activation pathway: Energy transfer from an iridium sensitizer produces an excited-state nickel complex that couples aryl halides with carboxylic acids. Detailed mechanistic studies confirm the role of photosensitization via energy transfer.

Metal-Free Catalytic Aromatic C–H Borylation

Synlett ◽  
2020 ◽  
Vol 31 (19) ◽  
pp. 1857-1861
Author(s):  
Hua Zhang ◽  
Li Wang
Keyword(s):  
Transition Metal ◽  
Recent Progress ◽  
Rapid Development ◽  
Transition Metal Catalysis ◽  
Mechanistic Studies ◽  
Metal Catalysis ◽  
Promising Alternative ◽  
Metal Free ◽  
History Of ◽  
Near Future

In recent decades, C–H borylation has undergone rapid development and has become one of the most important and efficient methods for the synthesis of organoboron compounds. Although transition-metal catalysis dominates C–H borylation, the metal-free approach has emerged as a promising alternative strategy. This article briefly summarizes the history of metal-free aromatic C–H borylation, including early reports on electrophilic C–H borylation and recent progress in metal-free catalytic intermolecular C–H borylation; it also highlights our recent work on BF3·Et2O-catalyzed C2–H borylation of hetarenes. Despite these recent advances, comprehensive mechanistic studies on various metal-free catalytic aromatic C–H borylations and novel processes with a wider substrate scope are eagerly expected in the near future.

Eu and Yb Excitation Mechanisms in ZnS, CaS, SrS and InP

1993 ◽  
Vol 301 ◽  
Author(s):  
M. Godlewski ◽  
K. Światek ◽  
B. Monemar
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Excited State ◽  
Exciton State ◽  
Experimental Results ◽  
Excitation Mechanism ◽  
Core State ◽  
Excitonic State ◽  
Excitation Mechanisms

ABSTRACTThe role of the excitonic excitation mechanism of the rare earth (RE) intra-shell emission is discussed. Two cases are analyzed. For Yb ion in InP 4f-4f emission of Yb3+ is induced by energy transfer from bound exciton state to the RE core state. For Eu in CaS and SrS RE emission is induced by carrier trapping directly to the excited state of Eu2+ ion. Also in this case the intermediate excitonic state may participate in RE excitation, as suggested by some experimental results.

scholarly journals Bond Forming Reactions Involving Isocyanides at Diiron Complexes

Inorganics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 25 ◽  
Author(s):  
Rita Mazzoni ◽  
Fabio Marchetti ◽  
Andrea Cingolani ◽  
Valerio Zanotti
Keyword(s):  
Transition Metal Catalysis ◽  
Organometallic Complexes ◽  
The Other ◽  
Coupling Reactions ◽  
Molecular Fragments ◽  
Carbene Ligands ◽  
Metal Catalysis ◽  
Bond Forming ◽  
Environmental Friendly ◽  
Catalyzed Reactions

The versatility of isocyanides (CNR) in organic chemistry has been tremendously enhanced by continuous advancement in transition metal catalysis. On the other hand, the urgent need for new and more sustainable synthetic strategies based on abundant and environmental-friendly metals are shifting the focus towards iron-assisted or iron-catalyzed reactions. Diiron complexes, taking advantage of peculiar activation modes and reaction profiles associated with multisite coordination, have the potential to compensate the lower activity of Fe compared to other transition metals, in order to activate CNR ligands. A number of reactions reported in the literature shows that diiron organometallic complexes can effectively assist and promote most of the “classic” isocyanide transformations, including CNR conversion into carbyne and carbene ligands, CNR insertion, and coupling reactions with other active molecular fragments in a cascade sequence. The aim is to evidence the potential offered by diiron coordination of isocyanides for the development of new and more sustainable synthetic strategies for the construction of complex molecular architectures.

Role of transition-metal catalysis in the formation of natural gas

Nature ◽  
1994 ◽  
Vol 368 (6471) ◽  
pp. 536-538 ◽  
Author(s):  
Frank D. Mango ◽  
J. W. Hightower ◽  
Alan T. James
Keyword(s):  
Natural Gas ◽  
Transition Metal ◽  
Transition Metal Catalysis ◽  
Metal Catalysis

scholarly journals Enantioselective transition metal catalysis directed by chiral cations

2021 ◽  
Author(s):  
Xinyi Ye ◽  
Choon-Hong Tan
Keyword(s):  
Transition Metal ◽  
Transition Metal Catalysis ◽  
Metal Catalysis ◽  
Organometallic Catalysis

Enantioselective transition metal catalysis directed by chiral cations is the amalgamation of chiral cation catalysis and organometallic catalysis.

scholarly journals Visible Light-Induced Excited-State Transition-Metal Catalysis

2019 ◽  
Vol 1 (5) ◽  
pp. 510-523 ◽  
Author(s):  
Rajesh Kancherla ◽  
Krishnamoorthy Muralirajan ◽  
Arunachalam Sagadevan ◽  
Magnus Rueping
Keyword(s):  
Excited State ◽  
Transition Metal ◽  
Visible Light ◽  
State Transition ◽  
Transition Metal Catalysis ◽  
Metal Catalysis

Heteroatoms moving protons: Synthetic and mechanistic studies of bifunctional organometallic catalysis

2010 ◽  
Vol 82 (3) ◽  
pp. 635-647 ◽  
Author(s):  
Douglas B. Grotjahn
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Structural Studies ◽  
Mechanistic Studies ◽  
Organometallic Catalysts ◽  
Nmr Data ◽  
Alkene Isomerization ◽  
Organometallic Catalysis ◽  
Catalytic Intermediates

Improved organometallic catalysts resulting from including ligands capable of proton transfer or hydrogen bonding are described. Pyridyl- and imidazolylphosphines accelerate anti-Markovnikov alkyne hydration and alkene isomerization and deuteration by factors of 1000 to more than 10 000. Evidence for proton transfer and hydrogen bonding in catalytic intermediates comes from computational, mechanistic, and structural studies, where 15N NMR data are particularly revealing.

Sign in / Sign up

Export Citation Format

Share Document